Lubricators in 3/4 scale

[bigdeal]

I'm considering building a Raritan or a Kozo A3 switcher. The Raritan doesn't use a lubricator (but has an odometer - too cool) but Kozo puts one in the A3.

Does a 3/4 inch locomotive really need a lubricator?

[gwrdriver]

Absolutely. Any steam engine will benefit from having cylinder lubrication and I wouldn't build one (of amy kind or size) without it. Why the Raritan doesn't use one I don't know (are you sure of that?) There are those who will say that oil is unnecessary, that "steam" is the lubricant, but I think the last of that bunch was institutionalized some time ago.

[Patrik]

even a little steam engine have a lubricatior

[bigdeal]

Thanks for the hints.

Kozo uses Walshaert's gear in the A3 and has 2 eccentrics inside the frame, one for the mechanical lubricator and one for the feed pump.

The Raritan uses slip eccentric gear with a rocker shaft to the outside, and has 3 eccentrics - one for the feed pump and one for each valve - and no lubricator in the plans.

The Raritan instruction book shows how to fit full Stevenson gear. If you did, there would be no room for an additional eccentric for a lubricator.

To be scale, the Kozo A3 would correctly use Stevenson gear, If I tried to fit it like the Raritan, there would be nowhere to put a lubricator.

What to do? [img]/ubb/images/graemlins/confused.gif"%20alt="[/img]

[john stewart]

Harry;

The Raritan uses cast iron pistons/cylinders/slide valves, and is saturated. You squirt a bit of oil in at the end of a run.

If you have ever seen a Raritan run, you'll know that they do indeed run like scalded cats. Fantastic little locomotive.

Why build one without a lubricator? For the beginner, a lubricator is more work (no matter what type) than not having one, so the locomotive gets on the rails faster. That's also the reason for the slip eccentric valve gear, and the lack of spring rigging, etc, etc...

Don't knock it, until you have seen one in action.

Cheers;

John Stewart
Ottawa, Canada.

[gwrdriver]

John, Read my post again, I didn't knock anything. I have seen a Raritan run. For those with a great deal of experience, who know what to expect if they don't take certain precautions and are willing to live with it, I say do whatever you want. But when someone with little or no experience (or so it appears) asks a question, I can only recommend that for the relatively small amount of work involved every engine should have a lubricator.

But in the case of the Raritan who needs an eccentric? Why not a simple hydrostatic lubricator? This would not only be a good learning exercise but a little extra insurance as well. It's so simple there's no excuse NOT to do one.

[bigdeal]

The Raritan and Kozo's A3 run the steam line inside the boiler from the dome to the front tube sheet, then a short tube inside the smokebox to the exhaust tee between the cylinders. How would one situate a hydrostatic lubricator?

[gwrdriver]

You'd have to address any given locomotive individually, but essentially the lubricator could be located anywhere you could gain nearby access to a live steam line that provided equal flow to both cylinders, that is before any split. I've seen locomotives with the lubricator located under the pilot beam plate with a filler cap protruding up through the plate and this is the first thing that comes to mind here, but there may be a better place. A hydrostatic will force oil up, down, or sideways, elevation doesn't matter. I have the articles for both the Raritan and the A-3 and I'll take a look when I can make time. I don't think this is the case here but what I don't advise is putting a lubricator in front of the throttle so that upon cool-down the vacuum created might draw oil back into the boiler.

[cbrew]

The hydrostatic lubricators do not need to be in the main steam line,
You can have one lubricator on each cylinder plumbed at the top of the valve chest
Take a look here

[gwrdriver]

Yes, Chris is right, in fact anywhere that oil can be introduced equally into the steam supply to the cylinders is OK. BUT documented experience (by many others) has shown that when ONE lubricator attempts to supply two cylinders in that way, that is feeding oil directly to the steam chests through a Tee'd line, that setup invariably favors one cylinder over the other leaving one "dry". Many great minds (not mine!) have tried to change this behavior without repeatable success. So for consistent and dependable lubrication I read that the oil must either be introduced into the steam line before the main steamline split (tee) or have one lubricator supplying the steam chest of each cylinder (ie two lubricators). What might very well work (you'll have to experiment with this) is to have one lubricator with two feed lines from a common reservoir. This is commonplace with mechanical lubricators but I've never seen this attempted with a hydrostatic lubricator. I can't think of a good reason why it wouldn't work. For best results your lubricator should have a needle flow adjustment valve otherwise they tend to blow too much oil through.

[cbrew]

I would not even try to plumb one hydro lubricator to two cylinders,
Unless it is BEFORE the tee
If you plumb at the valve chest then use two lubricators
I don’t even like using one mechanical lubricator with two outputs, because you can’t tell if both are working correctly.

Many may agree with me, I have spent way too much time and money building my engine not to run lubrication

[bigdeal]

Thank for the hints again. I thought it HAD to be in the main steam line.

Sooooo, if a guy was clever, he could maybe build it into the sand dome and use the sand lines as plumbing on a small locomotive? Or...maybe that is too much work for too little reward.